1. Field of the Invention
This invention relates to brake pads and more particularly to brake pads with a wear indicating device incorporated therein.
2. Description of the Prior Art
Conventional brake pads for motor vehicles include a support plate operably connected to an actuating mechanism and a layer of friction material, commonly referred to as a brake lining, carried on a face of the support plate and shaped to conform to a braking surface such as a brake disc or drum.
The friction material wears out through frictional contact with the braking surface and needs to be periodically replaced. If the friction material wears through, the support plate rubs against the braking surface and can damage the braking surface. Consequently, it is desirous to provide a warning signal when the friction material is worn thin. It is known to incorporate an electrical contact in the brake pad which contacts the braking surface when the friction material has worn to a dangerously low level thereby allowing activation of an electrical warning device such as a warning lamp on an instrument panel.
It is also known to position noise generating discs between the friction material support plate to create a warning signal.
The presently known warning devices generate only one single warning signal so that the operator of the vehicle has no indication as to the urgency with which the brake pad requires replacement. Additionally, the present electrical devices can be disabled in the event that the electrical leads to the contact become broken.
A warning system is needed that produces a first signal and a second distinct signal indicating a greater urgency for brake maintenance.